Method of and apparatus for manufacture of carbureted water gas



May 6, 1 952 Filed June 5, 1948 METHOD OF AND 0F CAR J s. HAUG 2,595,252

APPARATUS FOR MA BU ACTURE RETTED WATER G 2 SHEETS-SHEET l *Mm v Q lira/embr John S. Hawg by his flfiomeys I A- W.

May 6, 1952 J, 3, HAUG 2,595,252

METHOD OF AND APPARATUS FOR MANUFACTURE QF CARBURETTED WATER GAS Filed June 5, 1948 2 SHEETS$HEET 2 r Y s w b P h h h h 1M w m Q m S w m ms m mm m 9% m J, m V, 0 fi wan mm n fi I mm m I n H NS m. m w m mgg fl. m; m. w v Q h I I I IMQNI I I I I I I I \w I l o h Q; h a fi... U. J .1 n z z, w w 2, w mw k, $5 4 3 r %m I. m9 m I Q r. m f\' I I I I m g 5 m 3 M II am m m J. 8 8 n Mm x /u a m aw a NmN I My \m K III w NNMN %\w 4 m 65 $1 Patented May 6, 1952 minnows. A RA US FO M N FACTURE OF CARBURETED VVATE'R GAS John S. Hang, Philadelphia, Pa., assignpr to United Engineers & Constructors Inc Philadelphia, Pa., a corporation of Delaware Application Juhe 3, 1948, Serial No. 30,846

13 Claims. 1

The present invention relates to a method of and apparatus for the manufacture of car'- buret'ted Water gas. Its use is particularly advantageous iii the manufacture of carbuietted water gas wherein the enriching oil is a heavy oil or residuum which yields a relatively large proportion of coke on vaporization.

In the usual manufacture of carburetted water gas,- an ignited bed of solid fuel, such, for example, as coke, is alternately blasted with air and's'team in a cyclic operation. In the air blastl-ngstep of the cycle, termed the fblo'w', the temperature of the fuel bed is raised by combustion and heat is stored therein, for use in the steam blasting portion of the cyan, termed the run, in which blue water gas is formed by the endotherinic reaction of the steam with the hot carbon.

During the blow, the producer gas formed by the upward air blasting of the fuel bed with primary air is ignited with secondary air, and the burning gases are led through chambers contaming heatstorage material in which their heat is stored-. During the run, at least a portion of the 'blue' water gas issuing from the fuel bed is led along this path of stored heat and is carburet ted with hydrocarbon oil, such as petroleum oil, which is vaporized and cracked to oil gas by the storedh'eat in the presence of the blue water gas and excess steam from the fuel bed. i

Usually the runpe'riodof the cycle is divided into an up-run, in'wh-ich the steam passes upwardly tnroughthe fuel bed, the resulting up-run blue water gas being carburetted-in its passage through c'arburetting vessels; such as a carburetter and superhea-ter, and a down-run in which steam is passed downwardly through the fuel bed. The do'wmr'un is usually in; thefor'm of a back run m which steam is passed reversely through the carburetted water gas set, being superheated in passing through the carburettlng vessels prior to being passed downwardly through the fuel bed. The resulting back-run water gas is ledawa'y directly from the base of the fuel bed. During the downor back run step, hydrocarbon 011 may or not be introduced inwtne dawn or'b'ack run steam ana'pa sed therewith downwardly through the fuel bed, in a procedure com-- monly called an oil reforming step.

In modern carburetted water gas practice a cycle length of five'mi'nutes' is seldom exceeded, two to five minutes being the range" of cycle length-in usual practice with from three to four minutes more customary.

Anapproximate measure of the coke which a petroleum oil will yield upon vaporization in carburetted water gas practice is the; Conrad son carbon of the oil as determined by the method described in A. S. T. Standard 'Di89-4l.

When a petroleum 0', such, for example, as gas, oil, having a relatively low Gonradson carhim, for example, of below 1 or 2 %,;ls employed for enrichment; the usual practicehasbeen to admitthe oil during the up-run into a carburettor providedwith refractory checkerbrick, which affords a large highly heated surface for the va porization of the oil, the resulting mixed vapor phase being passed through a checkerbrick filled superheater for the continued'cracking or fixing of hydrocarbon components;thereof. c When heavy oil, having a relatively high Conradson carbon content above approximately 2%, such, for example,- as from 4 to 10 or 1-2 and higher, is employed for enrichment, the vaporization of the oil in a checkered carburettor becomes undesirable, due to the rapid plugging ofthe relatively narrow passages between the checkerbricks by deposited carbon. Since frequent interruptions of the normal cycle to burnout this carbon or to dispose of it otherwise very greatly reduce the gas making capacity of the apparatus, it became the usual practice, in the use of such heavy oil for enriching, to employ acarburetter substantially devoid of checkerbri'ck, at least downstream f-rom the zone of oil admission-therein.

Since it is difiicult tostore suificient heat in" the refractory lining of thecarburetter to effect the vaporization of all of the heavy oil usuallyrequiredfo-r enrichment, at the rate demanded by operation at high set capacities; it became a common practice to efiect the vaporization of a part of the heavy enriching oil by spraying it on to the top of the generator fuel bed during the up -run.

This latter procedure would be desirable even if all of the heavy oil could be eficiently handled in the carburetter, since the coke produced on the vaporization of the oil becomes a part of the generator fuel bed, andlmat-eri ally reduces the quantity of solid fuel which must be charged thereto. I 7 c 7 K In contrast to this, heavy oil whichis-sprayed into; the carbiiretter'for vaporization therein deposits eok'eofi thewalls and floor. thereof; on which surfaces its nuisance can derably' outweighs anyaovantages it may na essru l.

A principal object the present invention is to increase the proboltionbf the heavy enriching and/oi iforining'oih-whichmay be admitted to the generator; with a; reduction-of coke aepose tion inthe other portions of the set, and with increased utilization of oil coke as generator fuel.

The reduction of coke deposition in thee-arburetting vessels effects increased capacity in that it permits longer operation" of the setwithout shut down for cleaning, since withmodein mechanical grates the generators may be onerated for long periods without shutdown. There is an accompanied reduction in cleaning labor. The reduction of coke deposition improves the rate of heat transfer to and from the refractory heat storage material in the carburetting vessels, since the carbon acts as a heat insulator. This permits a greater proportion of run to blow in the cycle, with consequent further increase in set capacity. Inasmuch as the carburetter and superheater will operate more efficiently without a coating of carbon on their refractory surfaces, a reduction in carbon deposition therein reduces the vessel size required for a given quantity of oil employed per unit of gas produced. As to the carburetter, the reduction in oil vaporization therein permits a further reduction in size, with the possible elimination of any necessity for providing a carburetter in some cases.

However, full advantage cannot be taken of the addition of oil coke to the fuel bed and the reduction of carbon deposition elsewhere simply by admitting all of the heavy enriching oil to the generator top, in the manner in which part of the oil is admitted in present practice. In the usual methods of introducing heavy oil into the generator, it is merely heated to a temperature at which it can be readily handled, say 200 to 250 F. or somewhat higher. Under these conditions, 50% of the heavy enriching oil required for carburetting to a calorific power of, for example, 520 B. t. u. per cubic foot of finished gas is about the upper limit of the proportion of the total enriching oil which may be so vaporized, in the case of a typical Bunker C oil of approximately 10% Conradson carbon. When employing usual methods, if it is attempted to vaporize a much greater proportion than this on the generator top, a relatively impervious gummy layer is produced thereon, which greatly impairs the porosity of the fuel bed. The very poor fuel bed conditions produced cause highly non-uniform gas flow with channelling and increased blowing-over of fuel, and result in the loss of gas-making efficiency and capacity.

In accordance with the present invention, the enriching oil, such, for example, as a heavy oil of relatively high Conradson carbon, prior to introduction to the set, is preheated, preferably by waste heat from the gas set, in batches of relatively limited volume under pressure conditions sufliclently elevated to maintain the oil substantially as a liquid, to a temperature sufficiently elevated to cause the flash vaporization of a considerable proportion of the oil by the preheat upon reduction of the oil pressure to the pressure conditions existing in the carburetted water gas set. In usual practice the pressure conditions existing during the up-run on the down-stream side of the fuel bed top are but slightly above atmospheric pressure, for example, of the order of inches of water. During the back-run, the pressure conditions in the same portion of the set, which is then on the up-stream side of the fuel bed top, are somewhat higher because of the back pressure due to fuel bed resistance.

Each batch of oil undergoing preheating is displaced from the preheating apparatus to the set during a run period or periods by the succeeding batch and the volumes of the fluid way of the preheating apparatus through which the oil flows and of the oil piping from the preheating apparatus to the set are so proportioned with respect to the volume of oil per cycle required by the set that the oil is exposed to coking temperatures, prior to utilization, for a period of time 4 insuflicient to produce objectionable coking in said fluid way and piping.

Although other forms of apparatus may be employed, it is preferred to use preheating apparatus having a tubular fluid way or ways for the oil around which the heating gases flow in indirect heat transfer relation to the oil by way of the tube wall or walls.

During the blow, when no oil is flowing to the set, the batch of oil in the tubular way may be relatively quiescent except for flow due to convection, or the batch may be kept in motion through the fluid way by recirculation therethrough, while the heating gases pass through the preheating apparatus around the tube or tubes. When the oil is relatively quiescent during the blow, a larger portion of the heat transferred from the heating gases during the blow will be stored in the tube wall or walls and subsequently transferred to the oil during the run, when the il is flowin through the tube or tubes, than will be the case when the oil is recirculated during the blow.

During the portion of run in which the oil is admitted to the set, oil which has been relatively quiescent in the tube or tubes of the preheater or which has been recirculated therethrough is displaced to the set by oil of the succeeding batch to be preheated. In case the oil has been relatively quiescent in the tube or tubes, a considerable if not the major portion of the preheating is effected during the flow of the oil by the transfer thereto of heat which was stored in the tube wall or walls while the oil was relatively quiescent therein.

In accordance with the present invention, the preheating apparatus is arranged so that the volume of the oil passage therethrough in which the oil is exposed to coking temperatures does not exceed the volume of oil required by the set over a period of several cycles, for example, during three, or two cycles or more preferably one cycle, the smaller volumes bein particularly preferred the higher the temperature of preheat.

The degree of coking which will occur on prolonged heating under elevated temperature conditions will depend upon the characteristics of the oil, such as, for example, its Conradson carbon content. With typical heavy oils, coking temperatures may be considered to be temperatures above 600 F, such as, for example, from 600 to 850 F. and higher.

Preferably the apparatus is arranged so that the volume of the fluid way containing oil at a temperature above 650 F. does not greatly exceed that required by the set during several cycles, such as, for example, during three cycles, while that containing oil above 700 F. does not greatly exceed the oil required by the set during two cycles, and that containing oil above 750 F. does not greatly exceed the oil required by the set during one cycle, it being understood that a volume not greatly exceeding that required by the set during one cycle is the more preferred in any case.

Preferably a relatively large proportion of the heat above 60 R, which is required for the'fiash vaporization of the preheated oil, under set pressure conditions, is stored in the oil as preheat. such as the major portion thereof, for example, 60% or more, such as in excess of or even thereby very considerably reducing the quantity of heat which is required to be supplied in the set for oil vaporization, and very greatly increasing the quantity of oil which may be emciently vaporized per cycle in the top of the gener'ator, without unduly impairing fuel bed conditions.

The invention will be more particularly described in connection with the accompanying figures, which show, somewhat diagrammatically, rorms of the apparatus of the invention, chosen for illustration and in which Figure 1 shows, partly in elevation and partly in vertical section a three-shell carburetted water gas set to which is connected the apparatus of Figure 2.

Figure 2 shows, partly in elevation and partly in vertical section, one form of the oil preheating apparatus of the invention. Figure 2, for convenience, is shown in somewhat larger scale than Figure 1, but the two are to be considered in combination as forming one apparatus.

Figure 3 shows partly in plan and partly in horizontal section a modified high temperature on preheater.

Referring to Figures 1 and 2:

l is a generator, 2 a carburetter, 3 a superheater, and 4 a wash box of a carburetted water gas set. The upper portion of the generator is in gas communication with the upper portion of the carburetter by way of connection 5, while the lower portion of the carb'uretter is in gas communication with the lower portion of the superheater by way of connection 6.

The generator is illustrated as provided with the ignited bed I of solid fuel, for example of coke, which may be replenished through the coal hole branch 8, and which is illustrated as supported on the grate 9.

The generator is further illustrated as provided with the air blast connection 55, furnished with valve II, for upwardly blasting the fuel bed with primary air, and with the secondary air supply I2, provided with valve 13, for burning, above the fuel bed, the producer gas resulting from the primary air blast. The secondary air is illustrated as entering the upper portion of the generator tangentially through a plurality of connections l4. If desired, tertiary air may be admitted to the set as at I5.

The generator is further provided with steam supply connection l6, furnished with valve 17, for 'up-running through the fuel bed. Steam supply connection I8, provided with valve l9, supplies steam to the superheater top for backrunning through the set.

The superheater is illustrated as provided with the stack valve 20 and with the refractory checkerbrick 2|, while the carburetter is illustrated as devoid of checkerbrick. The refractory linings of the generator, carburetter and superheater are indicated at 22, 23 and 24 respectively.

The set is illustrated as provided with up-run gas take-off 25, provided with valve 26, leading from the superheater top to the'wash box, and with the back-run gas take-off 21, provided with valve 28, leading from the generator base to the wash box. Gas take-off 29, provided with valve 30, leads from the wash box to storage or other disposal.

The wash box is illustrated as provided with a valved liquid supply connection 3!, for supplying liquid such, for example, as water thereto, and with overflow connection 32, arranged to provide a liquid level 33 above the bottom of pipe 25 to furnish a seal therefor.

The generator is illustrated as provided with a spray 34, for spraying oil thereinto above. the fuel bed, and the carburetter is iitustrateu as pro- 6 vided with a spray 35, for spraying oil inte the upper portion thereof.

The previously described features are to be found in existing carburetted water gas sets. Such sets are frequently further provided with a blast gas take-off, such as 40, leading through waste heat boiler, such as 4 I, to a stack 42 byway of a boiler stack valve, such as 43. 44 indicates a boiler feed watersupply connection, while connections 45 and 45 lead to and from -'a steam drum (not shown).

In the apparatus illustrated in FigureJZ, theoil preheating means are "divided into a low temperature preheater 41 and a high temperature preheater 48. Low temperature preheater has a fluid way for heating gas which forms apart of the-path of the blast gases 'down stream .from the waste heat boiler, while the fluid way for heating gas of high-temperature preheater 48 forms a "part of the path of the blast gases upstream from the waste heat boiler.

Low temperature preheater is conventionally indicated as provided with a tubular way .for oil 49, formed of tubes connected in series by headers, which is supplied with oil under suitable pressure by pump 50, from supply line 51, by way of connection 52 leading to oil inlet 53. Oil outlet 54 of the low temperature preheater is connected, by way of line 55, with oil inlet 55 of high temperature preheater 48. High temperature preheater 48 is conventionally indicated as provided with-a tubular way for oil 51, formed of tubes connected in series by heaters, which is connected to oil inlet 55 and oil outlet 58.

The high temperature preheated 431s illustrated as provided with gas by-pass meanscomprising by-pass 5| leading from blast-gas takeoil 40 to gas connection 62 between preheater 48 and boiler 4|. By-pass El and connection 62 are illustrated as provided with dampers 63 and 64 respectively for blast gas flow control therethrough. Dampers 65, 65 and 6'! in branch bypass connections 68, 59 and i0, respectively,'a1so provide adjustable gas by-pass control. If desired, a damper may also be provided in connection 40 as at 10a. By the appropriate setting of the several dampers all or a predetermined fraction of the blast gas may be by-passed around all of the tubes or around a selected down-stream portion thereof.

From oil outlet 58, of preheater 48, oil line H leads to the generator of the 'carburetted water gas set as shown in Figure 1; Line H is provided with means for reducing the pressure on the'oil to cause its flashing bythe preheat therein, such, for example, as expansion valve 13. The flow'of oil through the preheaters to the set maybe measured by any suitable means, such, for ex-- ample, as a flow meter indicated at 14 in line, 55.

Since it may be necessary to introduce some of the preheated oil to the carburetter, line H may be connected with line 15, provided with expansion valve 16, leading into the carburetter top.

The following is an illustrative operation of the apparatus of Figures 1 and '2. With superheater stack valve 20 and back-run valve 28 closed and with boiler stack valve 43 open, with dampers 63, 6'5, 65 and 6'! closed and with damper 64 open, with oil valves 13 and i6 closed and with the tubes of preheater 41, oil line 55, the tubes of preheater 48, and oil lines H and 15 filled with a batch of heavy carburetting oil under sufiicient pressure to maintainit substantially as a liquid, the ignited fuel bed in the generator is blasted with primary air supplied threugii connection i0,

laising its temperature and storing heat therein.

The resulting producer gas is burned with secondary air supplied to the generator, above the fuel bed, through connections I2 and I4, and the resulting products of combustion are passed through the carburetter and superheater in series, thereby raising the temperature of the fuel bed top, the lining of the upper portion of the generator and of the carburetter, and the lining and checkerbrick of the superheater, and storing heat therein.

. i .From the superheater, the blast gases pass by way of connection 40 through the high temperature preheater 48, waste heat boiler M and low temperature preheater 11 to stack 42 and thence r;

to the atmosphere.

In passing throughpreheater 48, heat is transferred from the blast gases to the tube walls, which have a considerable heat storage capacity since they must have considerable thickness to;

withstand the oil pressures obtaining, and some heat is transferred from the walls to the relatively quiescent oil within the tubes. 7

On exit from preheater 48 the blast gases, som

what cooled by the transfer of heat to the tubes:

and the oil therein, pass through connection 62 and thence through waste heat boiler ii in which they are further cooled by the transfer of a further portion of their heat to the water in the boiler to raise steam.

From the waste heat boiler, the blast gases pass through the low temperature oii preheater M, flowing around its tubes 49, and transferring a further portion of their heat to the tubes and to the oil lying therein, before passing through the; i

open stack valve 63 and boiler stack 52 to the atmosphere.

At the end of the blow, the primary and secondary air blasts are shut off. Steam is supplied to the base of the generator through connection l8 and is passed upwardly through the fuel bed. The resulting water gas and excess steam purge through gas take-off as the combustion gases remaining in the set at the end of the blow. Stack valve 43 is then closed, and with valve 28 remaining closed and valves 26 and 30 open, the

up-run water gas is passed by way of connection 25 to the wash box and thence by way of connection 23 to condensing, purification, storage and/or other disposal;

As up-run water gas and excess steam flow in series through the upper portion of the generator, downwardly through the carburetter and upwardly through the superheater, pump 50 delivers oil from storage by way of lines 51 and 52 ,blow and forcing it into the generator top,

through line H and expansion valve '13 which is opened shortly after the beginning of the up-run.

The movement of the oil in the preheater tubes as it flows progressively from the low temperature heater into the high temperature heater and thence to the generator increases the rate of the transfer of heat from the walls of the tubes to the oil, with the result that the oil leaves the high temperature heater in a highly heated condition.

During the preheating operation the oil is maintained under sufficiently high pressure conditions to maintain it substantially in the liquid phase. Upon reduction in pressure on passing through valve 13 to the pressure conditions existing in the upper portion of th generator above the fuel bed, flash vaporization of the oil is effected with the deposition of residue therefrom upon the top of the fuel bed.

The liberated vapor phase material i admixed with the up-run blue water gas and excess steam which is simultaneously passing upwardly through the top of the fuel bed, the resulting mixture of blue water gas, excess steam and oil vapors passing through the carburetter and superheater in which the oil vapors are cracked with the formation of fixed oil gas and tar, the resulting carburetted water gas passing through take-off 29 from the wash box.

Residue from the flash vaporization of the oil is deposited on the fuel bed top where its coking is rapidly completed by heat stored in the fuel bed top and radiated from the generator top lining, aided by the sensible heat in the gases passing through the top of the generator.

At the end of the up-run, the steam supply to the base of the generator through connection [6 is shut off and with valve 26 closed and valve 28 open, steamis supplied to the top of the superheater through connection l8 and a back-run is vmade, the steam being superheated in passing reversely downwardly through the superheater, upwardly through the carburettor and thence downwardly through the fuel bed in the generator. The resulting back-run water gas and excess steam passes by way of connection 27 to the wash box and thence by way of connection 29 to storage. During this back-run step of the cycle, preheated oil may or may not'be supplied to the set, for example, to the generator top in the manner previously described.

In the event that oil is so admitted. during the back-run, the oil is flash-vaporized in the manner previously described in connection with the oil admission during the up-run, with the deposition of vaporization residue on the fuel bed top. The resulting oil vapors pass downwardly through the fuel bed with the back-run steam and are cracked therein, with the deposition of carbon resulting from the oil pyrolysis withinthe fuel bed. The resulting oil gas passes from the generator base through connection?! in admixture with the back-run water gas. The superheated back-run steam assists in completing the coking of the residue from the dash vaporization of the preheated oil.

After the back-run, with valve 26 open and valve 28 closed, a short uncarburetted up-run is made with steam supplied to the'generator base through connection It, the resulting combustible gas and excess steam passing by way of connection 25 to the wash box. Following this short uprun, a short air purge is made by supplying primary air to the base of the generator through connection [0, the resulting producer gas purging previously made up-ru water gas from the set through connection 25. After this air, purge, boiler stack valve 63 is opened and the repetition of the cycle begun with an open blow in which supply of primary air through connection 10 is continued.

During the oil admission to the set, either during the up-run or back-run or both, preheated oil may be supplied from the high temperature preheater to the carburetter by way of line ll, line I5, valve 76 and spray 35, for flash vaporization in the carburetter with the aid of heat stored inthe lining thereof.

In accordance with the present invention,-in. the illustrative operation above recited, the combined volume of the tubes of the high temperature preheater 48 and line II leading from preheater 48 to the generator (together with line 16, if employed) is, for illustration, approximately equal to the volume of oil admitted to the set during one cycle. Thus all of the oil which has previously lain quiescent in the tubes of the high temperature preheater 48 and in line. H (and in line I6, if employed) during the preceding blow is displaced from the preheater 48 and line II during the next succeeding run by oil entering preheater 48 through line 55 from preheater 41, so that the enriching oil is only exposed to relatively high preheating temperatures for a period of time equal to the cycle length.

Fresh oil from storage also displaces oil from the 10w temperature preheater 47. In the operation chosen for illustration, the oil is not heated to coking temperatures in the low temperature heater, therefore, it is not necessary to include the volume of the low temperature heater in the abovecombined volume.

In the apparatus illustrated in Figure 2, if it is desired to decrease the quantity of oil employed per cycle, the volume of oil exposed to relatively high preheat temperatures in preheater 48 may be decreased by closing damper 64 and opening one or more of dampers 65, 66 and 6'! thereby by-passing the blast gases around the tubes in down-stream portions of preheater 48 After the flash vaporization of the oil upon reduction in the pressure thereof, it may be desirable to effect at least a partial separation of the resulting vapor phase from the residual liquid phase in which the Conradson carbon content of the oil is concentrated, prior to the admission of the latter into the generator top, in order to avoid the entrainmen of the residual liquids and/or solids in the resulting vapor phase with the consequent carrying of the resulting carbon into the carburetter instead of efiecting its deposition on the fuel bed. This may be effected, for example, in the manner described in copending application Serial No. 785,672, filed November 13, 1947 by Gerald L. Eaton.

Re'erring to Figure 3:

This figure shows a modification of the high temperature preheater of Figure 2. As in Figure 2, 40 is the connection leading hot blast gases from the superheater 3 of Figure 1 to the high temperature preheater, which in Figure 3 is indicated generally as as and which is illustrated as provided with the refractory lining 9|. As in Figure 2, 62 is the connection leading blast gases from thedown-stream end of the high temperature preheater to a waste heat boiler (not shown in Figure 3). Unless specifically stated otherwise, in the following description the terms up-stream and down-stream refer to the flow of heating gases rather than to the. flow of liquids in the tubes.

While in the apparatus of Figure 2 the oil being preheated traverses the entire length of the series-connected tubes of the preheater, and means are provided for by-passing any desired proportion of the blast gases around a downstream portion of the tube length, in the apparatus of Figure 3 on the other hand, the blast 10 gases traverse the entire length of the preheater, while provisions are made for Icy-passing the oil around a predetermined down-stream portion of the tube length. As in Figure 2, the fluid Way through which the oil flows is in the form'of, series-connected tubes arranged in rows connected in series.

In the apparatus illustrated in Figure. -3 the;

provisions are such that the entering, oil may be admitted by way of the up-stream row of pairs of tube rows while by-passing all tube rows downstream from said row .of oil admission. For illustration certain of the tube rows are shown with successive tubes from top of the rows broken away to show the tube or tubes below.

Provisions are made to pass a cooling medium,

for example, water or steam, through the portion of the tube length not filled with oil to protect said tube length from destruction by the hot gases passed through the preheater.

As in Figure 2, 55 indicates the oil line leading to the high temperature preheater from the low tem erature preheater (not shown). In Figure 3, line '55 is shown connected to the bottom tube of alternate tube rows-95, 9?, 99, IOI, I03, I05

and. IE1, through valvesiilfl, Hi), vIII, H2, H3, I I4 and H5 respectively. Line 15 which supplies the coolingmedium, for example, water, is connected to the bottom tube of row 95, whileline I 48 which leads cooling medium away iscon' 40 nected with the bottom tube'of tube rows 96,913,.-

IQQ, I 32, I24 and Hi6 through'valves I25, I26,

I21, I28, I29 and I30 respectively. Tubes inthe' respective rows are connected in series, asby conventional oil still tube connections indicated at ISI. Pairs of adjoining tube rows are connected in series on one side of the preheater byconventional tube connections, indicated at I3Ia.,

similar to connection I3 I, while on the other side- Ififiand I3? rovided with valvesI-IL', I43, I44,

Hi5, IE5 and I l! respectively.

As in Figure 2, line H provided with valve I2 Water away is also connected to the down-stream 3 end (oil how) of tube row I08 through valve IIB. Tubes e 'tend into the header compartments I5) and HM, respectively on either side of the preheater in whi h are located the connections between the tubes and tube rows. Doors, such as I52 and IE3, provide access to the header'compartments for cleaning tubes andrnanipulating valves.

The bottom tubes in odd numbered tube rows may be cleaned on removal of plugs 'in"T I55 701 to I61 inclusive, while bottom tubes in even numbered tube rows may be cleaned onremova'l of plugs in T I82 to I81 inclusive.

In the operation of the apparatus of Figure 3, hot blast gasesfrom the set traverse the full 75, length of preheater 9d during the blow period of the cycle. During this period enriching oil undergoing preheating is lying quiescent in the tube row into which the oil is admitted through line 55 and in tube rows down-stream (oil flow) therefrom. The temperature of the quiescent oil is raised during the blasting period by heat transfer from the blast gases which also store heat in the tube walls.

If, for example, oil is being admitted from line 55 into tube row 99, valve I I I is open, while valves I09, H0, H2, H3, H4 and H5 are closed. Valve I43 is also closed while valves I42, I44, I65, I46 and I4? are open. Tube rows 99 to I08 inclusive together with the connections therebetween are filled with oil.

When oil is admitted into the preheater 90 from line 55 by wayof tube row 99, the tube rows downstream from tube row 99 are flooded with water from line I5, by way of valve 89 and the lower tube of tube row 95, valve M2 being open as previously stated, and valves I25, I 21, I20, I29 and I30 being closed. Water passing through the down-stream tube rows leaves the preheater by way of the bottom tube of tube row 98 through valve I26 and connection I48.

During the blow the blast gases store a portion of their sensible heat in the metal of the tube walls while heat is also transferred therethrough to the quiescent oil lying in the up-stream tubes and to the water in the down-stream tubes.

With the termination of the open blow, the passage of gases through preheater 90 ceases. However, heat transfer to the oil from the tube walls continues during the run.

With the inception of the oil admission portion of the run, valve I2 being open, the batch of oil in preheater 90 and connection 'II is displaced to the set by another batch of oil delivered to tube row 99, by way of line 55 from the low temperature preheater (not shown). The velocity of the oil through the tubes is preferably sufilciently high-to cause turbulent flow, favoring high rates of transfer, to the oil, of heat previously stored in the tube walls.

The volume of oil contained in tube rows 99 to I08 inclusive, with their connections, and line H leading to the set is, for illustration, approximately equal to the volume of oil required by the set during one cycle of operation. Therefore,

prior to utilization the oil is maintained under.

relatively high temperatures of preheat for a periodof time not materially exceeding the cycle length, permitting a relatively high degree of preheat without objectionable coking.

Those skilled in the art will understand how to provide appropriate surface-volume relationship in the tubes to effect the desired heat transfer to the oil within the available time under the other conditions obtaining.

With the employment of up-stream tube rows 99 to I08 inclusive for oil preheating, downstream tube rows 98 to 95 inclusive are protected by flooding with water passed from line I5, by way of valve 89 to the bottom tube of tube row 95, the heated water leaving by way of the bottom tube of tube row 98, and thence through valve I26 and line I48.

The water passed through the down-stream tubes may be passed therethrough at a constant rate throughout the cycle, or at a varying rate, for example, so as to provide a substantially constant exit water temperature, the rate of flow being increased during the open blow and decreased during other portions of the cycle.

Valve I16 in oil line 55 controls the oil inlet 12 to the high temperature heater. Connection H1 provided with valve I18 may be employed for supplying steam for purging out line I I.

If desired, steam may be raised in the downstream tubes which are not employed for oil preheating, or steam may be passed therethrough as a cooling medium, the resulting superheatedsteam being employed in the water gas set if desired.

The following is a specific example of the method of the invention employing a -3-she1l ft. 1. D. carburetted water gas set and preheating apparatus similar to that described with a high temperature preheater similar to that of Fig.3" and with a cycle of operations similar to-that described above.

Length of cycle minutes 4 Percent of cycle- Open blow 42- Up-run 1 30 Back-run 2l Last-up-run fi- Blast purge .3 Approximate average temperature of blow gases, F.:

High temperature preheater- Gas inlet 1400 Gas outlet 1120' Low temperature preheater Gas inlet 630 Gas outlet 500 Average blow gas production (taken as if measured at 60 F. and at 760 min. Hg absolute pressure) cu. ft./min. 30,000

Carburetting oilBunker C oil of the following characteristics:

Water Trace Sp. gr., 60 F 0.970 Sp. gr., API 13.8 Viscosity Saybolt Furol, 60 cc.,

50 C.-sec. 4.84 Insoluble in benzol, percent by weight 0.25 Flashpoint--Peusky-Martens 253 Conradson carbon, percent by weight 10.1 Ash, percent by weight 0.128 B. t. u./lb. 18.547 Sulfur, percent by weight 0.82 Distillation Percent 425450 F 0.5 450-500 F 0.5 500-550 F 1.5 550-600 F. 05.0 600-650 F 12.0 650-700 F 4.5 Over 700 F 4 5 m 88.0 Oil per cycle -gal Rate of oil admission to set gal./min 12'7- Ave. velocity of oil flow during oil admission period ft./sec 13 Approximate capacity of oil filled portion of high temperature preheater-during blow gal 122 Approximate capacity of line to set gal 8 Oil to generator per cycle gal 96 Oil to carburetter per cycle gal 24 Ave. oil temperature:

Inlet to low temperature preheater TL. 250 Outlet of low temperature preheater TL. 450 Outlet of high temperature preheater 1 Oil admission, 25.5.

13 Oil pressure-P. s. i. g.:

Inlet to low temperature preheater 250 Preheater side of expansion valve 200 Preheater tubes, 2" I. D.:

Portion of high temperature-preheater filled with oil Tube rows l Tubes/row Total tube length including connections-ft. .l 748 Portion of high temperature preheater flooded with water- Tube rows 4. Tubes/row 10 Total tube length including connectionsft. 300

Although the invention, for illustration, has been described in connection with the use of a high temperature and a low temperature preheater on the up-stream and down-stream sides respectivelyof the set waste heat boiler, it is not limited to the use of any particular number of preheaters. Only one preheater may be employed if desired, and the preheating medium need not be the waste combustion gases from the set. For example, direct firing may be employed, in which case the heating gases may be passed through the preheating apparatus continuously instead of only during the blow. V The heating gases may also pass through the preheater during the run, when a plurality of sets are in stepped operation and the waste blow gases from one set are passed through the preheater during the run of another set to which oil is being de livered from the preheater.

Further, 'if desiredythe high'temperature oil preheater may be so located as to permit the heating of the oil therein by the hot up-run water gasas wellas by the blow gases. For example, the high temperature'oil preheater may take the form of a coil located in anextension of the superheatertop so that the relatively quiescent oil in the coil during the blow is heated by the blast gas'flowing around the coil on the way to the waste heat boiler and the flowing oil in the coil during the up-run is heated by the hot up-run carburetted water gas flowing around the coil on its way from the fixing surfaces of the superheater to the'wash'box without passing through the waste heat boiler.

If desired in the operation of the low temperature and high temperature oil preheaters'arranged in series in the oil flow to the set, the temperature to which the oil is heated in the high temperature heater may be limited and overheating avoided, by by-pasing a suitable predetermined proportion of the feed oil' around the low temperature preheater to the high temperature preheater, thus reducing the temperature of the oil fed to the latter, and thereby reducing the maximum temperature attained by the oil in the high temperature preheater, other conditions being the same.

The particular cycle of operation given, for illustration, above may be widely varied as to the proportion and arrangement of cycle steps and as to the specific cycle steps employed, as will be understood by those skilled in the art to which this invention pertains. Oil .may be introduced, if desired, to the generatorv and/orelsewhere duringa down or back-run and reformed in passage through the fuel bed. Down or back-blasting with air may be employed. Blow-runs may be employed, if desired, in either up-air blasting or in down or back-blasting'steps, and oilfimeyrbeadmitted to the generator and/or elsewhere: .dur-

ing a blow-run. Those skilled in theart will readily understand how the water gasxset illustrated in the figures readily understood thateven when preheatingoilv to relatively high temperatures it may be necessary to introduce a, part. of the liquid oil elsewhere, such, for. example, astothe carburetten, especially when a. relatively large. quantityof oil per houris required.

While. it ispreferred to preheat to a relatively.

high temperature. substantially all of the oil required, .it will be readily understoodthat some of the advantages of the invention may be obtained. even though a portion of the oil is not so preheated, and even though the oil be not heated to the maximum practical temperature.

It is preferred to introduce the secondary air for the combustion of the producer gas generated during the upward air blasting of the fuel bed, above the fuel bed, so as to burn the producer gas in contact with the fuel bed top and the generator crown; and it is preferred to introduce this air tangentially, as previously described, as in such case fresh air swirling in contact with cartroducing it to the carburetter directly, orinto the generator-carburetter connection.

It is preferred to carry the preheating of the oil to an average temperature above approxi- The preferred time of exposure of the oil to high preheating temperature is less the higher the Conradson carbon of the oil other conditions being the same.

In the claims as in the preceding description, unless otherwise specifically stated the terms down-stream and up-stream" refer to the direction of gas flow rather than oil flow.

The subject matter of this application isan improvement on the Method and Apparatus for the Manufacture of Carbureted Water Gas dis-- closed and claimed in the copending application of Gerald L. Eaton, Serial No. 785,672, filedNovember 12, 1947.

I claim:

1. In the cyclic manufacture of carburetted.

water gas by a blow and run process which comprises during a heating period of the cycle'blast-.

ing an ignited bed of solid fuel with air tora'ise the temperature thereof and to store'heattherein, burning the resulting producer gas with secondary air and storing its heat by leading the products of combustion along a heat storage path in contact with refractory heat storage material,

arranged therein, and during a carburetted water gas generating period of the cycle utilizing a portion of the heat stored during the blow in the endothermic reaction of steam with the fuel bed to generate blue Water gas, and simultaneously utilizing another portion of the stored heat for the gasification of petroleum oil in the presence of steam and of said blue water gas; the improvement comprising preheating said petroleum oil prior to gasiflcation by subjecting, during the blow period of the cycle, a relatively quiescent batch of said oil, retained in metal tubes in a preheating zone, to indirect heat transfer from said hot combustion products passed through said preheating zone; and during a run period of the cycle fiowingoil preheated to a temperature above approximately 600 F. and at a pressure sufficiently elevated to maintain said oil substantially in liquid phase at said temperature of preheating, from said preheating zone to the oil gasiflcation zone of the carburetted water gas-generating system while replenishing said preheating zone with oil'to be preheated therein during the subsequent blow period, and reducing the pressure on said oil between said preheating zone and said oil gasification zone to cause the flash vaporization of a considerable proportion of the preheated oil into said oil gasiflcation zone by reason of the preheat therein with the deposition of unvaporized material upon the top of said fuel bed, the volume of preheated oil in the system at any time ,at a temperature above approximately 600 F. not

exceeding the volume of said preheated oil utilized in said process within three successive cycles.

2. A process according to claim 1, in which volume of preheated oil in the system at any time at a temperature above approximately 608 F. does not considerably exceed the volume of said preheated oil utilized over the period of two successive cycles of said carburetted water gas manufacture.

3. A process according to claim 1 in which the volume of preheated oil in the system at any time at a temperature above approximately 600 F. is not considerably greater than the volume of said preheated oil utilized per cycle in said carburetted water gas manufacture.

4. A process according to claim 1, in which said oil preheating zone is divided into a relatively low temperature oil preheating zone and a relatively high temperature oil preheating zone with'oil flowing from said low temperature we heating zone to said high temperature preheating zone and thence to said oil gasification zone during a run portion of the cycle; said oil in said zones being heated by hot waste blast products flowed therethrough in heat transfer relation to the oil therein during the blow portion of the cycle and generally counterfiow to the direction in'which the oil flows therein during the run portion of the cycle, a portion of the heat contained in said blast gases being abstracted therefrom in a steam generating zone intermediate said high and'low temperature oil preheating zones in the blast gas flow.

5. A process according to claim 1, in which said oil preheating Zone is divided into a relatively low temperature oil preheating zone and a relatively high temperature oil preheating zone with oil flowing from said low temperature preheating zone to said high temperature preheating zone and thence to said oil gasiflcation zone during a run portion of the cycle; said oil in said zones being heated therein by hot waste blastproducts: flowed therethrough from said oil gasification zone in heat transfer relation to the and generally counterflow to the direction in which said oil flows during the run portion of the cycle, a portion'of the heat contained in said blast gases being abstracted therefrom in a steam generating zone intermediate said high and low temperature oil preheating zones in the blast gas flow, and said oil also being heated while flowing through said high temperature preheating zone to said oil gasiflcation zone during said run por tion of the cycle by hot up-run carburetted water gas passed from said oil gasification zone in heat transfer relation to said oil in said high temperature preheating zone during an up-run portion of the cycle.

6. A process according to claim 1, in which said oil preheating zone is divided into a relative- 1y low temperature zone and a relatively high temperature zone with oil flowing from said low temperature preheating zone and thence to said oil gasification zone during a run portion of the cycle; said oil in said zones being heated by hot waste blast products flowed therethrough in heat transfer relation to the oil therein during the blow portion of the cycle and generally counterflow to the direction in which said oil flows during the run portion of the cycle, a portion of the heat contained in said blast gases being abstracted therefrom in a steam generating zone intermediate said high and low temperature oil preheating zones in the blast gas flow, and modifying the temperature to which said oil is heated in said high temperature zone by by-passing a predetermined proportion of the oil feed around said low temperature preheating zone to said high temperature preheating zone.

'7. In the cyclic manufacture of carburetted water gas by a blow and run process which comprises during a heating period of the cycle blasting an ignited bed of solid fuel with air to raise the temperature thereof and to store heattherein, burning the resulting producer gas with secondary air and storing its heat by leading the products of combustion along a heat storage path in contact with refractory heat storage material arranged therein, and during a carburetted water gas generating period of the cycle utilizing a portion of the heat stored duringthe blow in the endothermic reaction of steam with the fuel bed to generate blue water gas, and simultaneously utilizing another portion of the stored heat for the gasification of heavy petroleum oil in the presence of steam and of said blue water gas; the improvement comprising preheating said heavy petroleum oil prior to gasiflcation by maintaining a relatively quiescent batch of said oil within tubular metal walls in a preheating zone during the blow period of the cycle in indirect heat transfer relation through said walls with waste products of combustion passed through said preheating zone from said path of stored heat, and during a run period of the cycle displacing oil preheated to a temperature above approximately 600 F. to the oil gasiflcation zone of the carburetted water gas-generating systemfrom said preheating zone with oil to be preheat-' ed therein during the subsequent blow period, said oil in said preheating zone being under sufiiciently elevated pressure to maintain said oil substantially in liquid phase at said temperature of preheating; and reducing the pressure on said preheated oil flowing from said preheating zone to said oil gasification zone to cause the flash vaporization of a considerable proportion of said preheated oil into said oil gasification zone by reason of the preheat therein with the deposition of residue from said flash vaporization on the top of said fuel bed, at least a portion of said flow of oil from said preheating zone to said oil gasification zone occurring during an up-run period of the cycle with the cracking of the resulting vapor phase hydrocarbon material in said path of stored heat in the presence of up-run blue water gas and steam passing simultaneously therethrough, and'the volume of preheated oil in the system at any time at a temperature above approximately 600 F. not exceeding the volume of said preheated oil utilized in said process within three successive cycles.

8. In a process for the manufacture of carburetted water gas by a cyclic blow and run method the improvement comprising preheating carburetting oil prior to utilization in said process by retaining a batch of said oil of relatively limited volume in a relatively quiescent state Within tubular metal walls in a preheating zone in indirect heat transfer relation with hot waste combustion products from said process passed through said preheating zone in contact with the outside of said tubular walls during a blow period of the cycle thereof, during a run period of said cycle displacing said batch of oil from said preheating zone to said utilization zone by a succeeding batch of oil to be preheated during the subsequent blow-period, said oil flowing within said tubular walls in said preheating zone in a direction generally counter-current to the flow of heating gases through said preheating zone and leaving said preheating zone at a temperature above approximately 600 F., said oil being held during preheating under sufiiciently elevated pressure to maintain it substantially in liquid phase at said temperature of preheating; reducing the pressure on said preheated oil in transit to the zone of oil utilization of the carburetted water gas-generating system to cause the flash vaporization of at least a considerable proportion of said preheated oil by reason of the preheat therein in said zone of oil utilization; the volume of oil at a temperature above approximately 600 F. retained within said tubular walls and within the oil passage from said preheating zone to said zone of utilization not at any one time greatly exceeding the volume of said preheated oil utilized in said process during one cycle thereof.

9. Oil preheating apparatus for carburetted water gas sets operating in blow and run cycles, comprising a heat exchanger having fluid ways therethrough for oil under-going preheating and for hot gas respectively in indirect heat transfer relation one to another, the oil passing through a tubular metal way about which the hot gas flows; gas conduit and flow control means for passing hot gas from the set through the gas way of said heat exchanger selectively during blow periods of set operation; oil impulsion, conduit and flow control means for delivering carburetting oil under elevated pressure into and from spaced portions respectively of said tubular way and thence through pressure reducing means to said set selectively during run periods of set operation, and for retaining a batch of said oil under elevated pressure in said tubular way selectively during blow periods of set operation; and fluid by-pass means for varying the length of travel of at least a portion of at least one of said fluids through said heat exchanger to vary the heat transfer from said hot gas to said oil.

10. Apparatus according to claim 9 in which said heat exchanger is provided with valved conduit means communicating with the gas way thereof at spaced intervals therealong for bypassing heating gas around a selected downstream portion of said tubular way.

11. Apparatus according to claim 9 in which said heat enchanger is provided with valved conduit means for selectively by-passing oil around a portion of the path of the hot gases through said heat exchanger.

12. Apparatus according to claim 9 in which said heat exchanger is provided with valve means arranged at spaced intervals along said tubular way for selectively dividing said tubular way into up-stream and down-stream portions of variable length, means for selectively passing carburetting oil into and through one of said portions for preheating therein, and means for selectively flooding the other portion with a cooling medium other than said carburetting oil to protect it from destruction by said hot products of combustion.

13. Oil preheating apparatus for carburetted water gas sets operating in blow and run cycles, comprising a heat exchanger having fluid ways therethrough for oil undergoing preheating and for hot gas respectively, in indirect heat transfer relation one to another, the oil passing through a tubular metal way about which the hot gas flows; oil impulsion, conduit and flow control means for delivering carburetting oil under elevated pressure, into and from spaced portions respectively of said tubular way and thence through pressure reducing means to said set selectively during run periods of set operation, and for retaining a batch of said oil under elevated pressure in said tubular way selectively during blow periods of set operation; gas conduit and flow control means for passing hot products of combustion from said set through the gas way of said heat exchanger during blow periods of set operation in a direction generally counter-current to'the flow of oil during run periods of set operation; and fluid by-pass means for varying the length of travel of at least a portion of at least one of said fluids through said heat exchanger to vary the heat transfer from said hot products of combustion to said oil.

JOHN S. HAUG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,053,074 Vuilleumier Feb. 11, 1913 1,351,859 Lowe et al. Sept. 7, 1920 1,745,454 Schwarz Feb. 4, 1930 1,824,215 Kirschbraun Sept. 22, 1931 1,876,965 Kopp Sept. 13, 1932 1,955,774 Sachs Apr. 24, 1934 1,996,167 Nagel Apr. 2, 1935 FOREIGN PATENTS Number Country Date 582,019 Germany Aug. 27, 1931 OTHER REFERENCES A l extbook of American Gas Practice, Morgan, 2nd edition (1931), published by J. J. Morgan, Maplewood, N. J vol. I, pp. 499 and 545. 

1. IN THE CYCLIC MANUFACTURE OF CARBURETTED WATER GAS BY A BLOW AND RUN PROCESS WHICH COMPRISES DURING A HEATING PRERIOD OF THE CYCLE BLASTING AN IGNITED BED OF SOLID FUEL WITH AIR TO RAISE THE TEMPERATURE THEREOF AND TO STORE HEAT THEREIN, BURNING THE RESULTING PRODUCER GAS WITHE SECONDARY AIR AND STORING ITS HEAT BY LEADING THE PRODUCTS OF COMBUSTION ALONG A HEAT STORAGE PATHIN CONTACT WITH REFRACTORY HEAT STORAGE MATERIAL ARRANGED THEREIN, AND DURING A CARBURETTED WATER GAS GENERATION PERIOD OF THE CYCLE UTILIZING A PORTION OF THE HEAT STORED DURING THE BLOW IN THE ENDOTHERMIC REACTION OF STEAM WITH THE FUEL BED TO GENERATE BLUE WATER GAS, AND SIMULTANEOUSLY UTILIZING ANOTHER PORTION OF THE STORED HEAT FOR THE GASIFICATION OF PETROLEUM OIL IN THE PRESENCE OF STEAM AND OF SAID BLUE WATER GAS; THE IMPROVEMENT COMPRISING PREHEATING SAID PETROLEUM OIL PRIOR TO GASIFICATION BY SUBJECTING, DURING THE BLOW PERIOD OF THE CYCLE, A RELATIVELY QUIESCENT BATCH OF SAID OIL, RETAINED IN METAL TUBES IN A PREHEATING ZONE; TO INDIRECT HEAT TRANSFER FROM SAID HOT COMBUSTION PRODUCTS PASSED THROUGH SAID PREHEATING ZONE; AND DURING A RUN P ERIOD OF THE CYCLE FLOWING OIL PREHEATED TO A TEMPERATURE ABOVE APPROXIMATELY 600* F. AND AT A PRESSURE SUFFICIENTLY ELEVATED TO MAINTAIN SAID OIL SUBSTANTIALLY IN LIQUID PHASE AT SAID TEMPERATURE OF PREHEATING, FROM SAID PREHEATING ZONE TO THE OIL GASIFICATION ZONE OF THE CARBURETTED WATER GAS-GENERATING SYSTEM WHILE REPLENISHING SAID PREHEATING ZONE WITH OIL TO BE PREHEATED THEREIN DURING THE SUBSEQUENT BLOW PERIOD, AND REDUCING THE PRESSURE ON SAID OIL BETWEEN SAID PREHEATING ZONE AND SAID OIL GASIFICATION ZONE TO CAUSE THE FLASH VAPORIZATION OF A CONSIDERABLE PROPORTION OF THE PREHEATED OIL INTO SAID OIL GASIFICATION ZONE BY REASON OF THE PREHEAT THEREIN WITH THE DEPOSITIOPN OF UNVAPORIZED MATERIAL UPON THE TOP OF SAID FUEL BED, THE VOLUME OF PREHEATED OIL IN THE SYSTEM AT ANY TIME AT A TEMPERATRE ABOVE APPROXIMATELY 600* F. NOT EXCEEDING THE VOLUME OF SAID PREHEATED OIL UTILIZED IN SAID PROCESS WITHIN THREE SUCESSIVE CYCLES. 